In U.S. Pat. No. 4,673,421 issued June 16, 1987, an installation has been disclosed including at least one horizontal conduit (or pipe) system which carries the gases to the tower above the exchange body, the water distribution system and the drift eliminators. The conduit is formed at its top or uppermost level with a slot which extends over almost the entire length thereof. Above the conduits are tanks which receive the gases through the slot, and which discharge the gases horizontally into the tower through drop separator panels.
The gases at the piping inlet have a relatively high speed (or first velocity) which is usually 15 to 25 meters per second, and the gases are discharged into the tower at a relatively low speed (or second velocity). This second velocity must be between a lower limit and an upper limit, between which the drop separators are efficient. These limits are e.g. 3 meters per second and 6 meters per second, respectively.
The speed of the gases at the outlet of the installation has to be kept as uniform as possible both along the panels and up them.
In a first embodiment of the installation known in the art, uniformity of the speed of the gases flowing in the longitudinal direction of the piping is attempted by keeping the slot narrow. Unfortunately, this produces a relatively large pressure drop when the gases flow from the conduit into the tanks. This arrangement has the following consequences: first, a considerable amount of energy is consumed to overcome the pressure drop that occurs when the flue gases pass through the slot; and, second, it is difficult to assure that the range of the second velocity will be as narrow as desired.
In a second embodiment of the installation known in the art, the slot is formed relatively wide. In this arrangement, uniformity of the speed (or velocity) of gases leaving the drop separator panels is obtained by disposing deflectors inside the conduit (or pipe) system. In these cases, the uniformity of gas speed is very satisfactory; however, the deflectors are very expensive. Also, such an arrangement makes replacement and repair of the deflectors difficult and costly. Finally, such deflectors are not readily adjustable for various specific needs.
Thus, it can be seen that there remains a need for a device for distributing gases from the piping (or conduit) to the tanks such that: first, the flow rate is substantially the same all along the pipe system; second, the gas flow at the tank inlets enables the gases to be sufficiently uniformly distributed up the drop separator panels disposed in the side surfaces of the tanks; and third, the device may be fabricated and maintained relatively inexpensively.